1. Field of the Invention
The present invention relates to devices, systems, and processes useful for exploration of hollow body structures, particularly those areas accessed through a tortuous, unsupported path. More particularly, the present invention relates to a system and method for navigation of an endoscope having a steerable tip.
2. Description of Related Art
Endoscopes are frequently used for medical exploratory procedures, either alone or in combination with an overtube for aiding the insertion of the endoscope. When an overtube is used it may be fully inserted in a single step prior to the insertion of the endoscope. The overtube and endoscope may also be incrementally inserted in an alternating fashion.
Overtubes may have a controllable rigidity in order to facilitate their introduction and to provide a firm guide for subsequent insertion of an endoscope. An overtube with controllable rigidity is typically in a relaxed state during its insertion or retraction in order to minimize the force transmitted to the body in which it resides. During the insertion or retraction of an endoscope through the overtube, the overtube is maintained in a rigidized state.
In addition to controllable rigidity, the prior art also teaches the use of a steerable tip for achieving a favorable contact angle between the inserted device and the body in which it is being introduced. Steering may be achieved by the use of control wires or by rotation of the inserted device.
Controllable rigidity and steering in prior art medical exploratory devices are used to minimize the forces applied to the body into which the exploratory device is inserted (e.g., a colon). Steering provides a low contact angle with a body surface and minimized rigidity reduces the force transmitted at sites of contact during movement of the inserted device.
Although the prior art has recognized the desirability of reducing the forces applied to a body being explored, present medical exploratory devices typically depend upon a finite reactive force from the body under investigation during use. Unfortunately, even a reduced contact force has the potential for patient discomfort and tissue trauma.
An example of a potential operator error associated with an incremental advance system is that involving excessive advancement of an endoscope with a steerable tip within a rigidizable overtube. Excessive advancement of the endoscope exposes a section of the endoscope that is not steerable and thus the tip may be inadvertently directed at a large contact angle against the wall of the body being explored. Although the prior art teaches various methods for reducing contact discomfort, a large contact angle resulting from a poorly directed tip may be difficult to overcome. The prior art frequently relies upon excessive advancement in combination with reaction forces from tissue walls to advance an instrument.
Thus, a need exists for system and method for medical exploration that does not depend upon reactive forces from the body being explored. There is also a need for a system prevents operator error through excessive advancement of an insertable device. It is also desirable that such a system be capable of providing free-space navigation interchangeably for endoscopes and other tools.